Analysis of intraspecific and interspecific interactions between the invasive exotic tree-of-heaven (Ailanthus altissima (Miller) Swingle) and the native black locust (Robinia pseudoacacia L.)

Invasive exotic plants can persist and successfully spread within ecosystems and negatively affect the recruitment of native species. The exotic invasive Ailanthus altissima and the native Robinia pseudoacacia are frequently found in disturbed sites and exhibit similar growth and reproductive characteristics, yet each has distinct functional roles such as allelopathy and nitrogen fixation, respectively. 1) A four-month full additive series in the greenhouse and 2) spatial point pattern analysis of trees in a silvicultural experiment were used to analyze the intraspecific and interspecific interference between these two species. In the greenhouse experiment, total biomass responses per plant for both species were significantly affected by interspecific but not by intraspecific interference (p <0.05). Competition indices such as Relative Yield Total and Relative Crowding Coefficient suggested that A. altissima was the better competitor in mixed plantings. Ailanthus altissima consistently produced a larger above ground and below ground relative yield while R. pseudoacacia generated a larger aboveground relative yield in high density mixed species pots. However, R. pseudoacacia exhibited more variation for multiple biomass traits, occasionally giving it an above ground advantage in some mixed species pots. Analysis of spatial point patterns in the field with Ripley's K indicated that the two species were positively associated with each other along highly disturbed skid trails in the majority of the field sites. Locally, increased disturbances could lead to more opportunities for A. altissima to invade, negatively interact with R. pseudoacacia (as was evident in the greenhouse study), and become established in place of native species.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Biology

Department dc:contributor.department

Biology

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2002

Author dc:creator

• Call, Lara J.

Chair dc:contributor.committeechair

• Nilsen, Erik T.

Committee members dc:contributor.committeemember

• Jones, Robert H.
• Porter, Duncan M.

• Ripley's K statistic
• De Wit replacement
• full additive design
• spatial point patterns
• invasive plants
• plant competition
• functional types
• plant interference

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-05162002-132819

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/32845